National Instruments Welding System 321645c-01 사용자 설명서

Chapter 2

Function Reference — CTR_EvRead

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 National Instruments Corporation

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NI-DAQ FRM for PC Compatibles

CTR_EvRead

 reads the current value of the counter without disturbing the counting process 

and returns the value in count. 

CTR_EvRead

 also performs overflow detection and returns the 

overflow status in overflow. Overflow detection and the significance of count depend on the 
counter configuration. 

For NI-DAQ to detect an overflow condition, you must configure the counter for TC toggled 
output type and positive output polarity, and then you must configure the counter to stop 
counting on overflow (cont = 0 in the 

CTR_EvCount

 call). If these conditions are not met, the 

value of overflow is meaningless. If more than one counter is concatenated for event-counting 
applications, you should configure the lower-order counters to continue counting when 
overflow occurs, and overflow detection is only meaningful for the highest order counter. 
count, returned by 

CTR_EvRead

 for the lower-order counters, then represents the module 

65,536 event count. See Event-Counting Applications in Chapter 3, Software Overview, in the 
NI-DAQ User Manual for PC Compatibles for more information.